Hydrocatalytic desulphurisation of petroleum hydrocarbons



Frederick William Bertram Porter and Roy Purdy Nortl1-.

cott, Sunbury-on-Thames, England, assignors to The British Petroleum Company Limited No Drawing. Application November 16, 1954, Serial No. 469,310

Claims priority, application Great Britain November 24, 1953 4 Claims. (Cl. 196-28) This invention relates to the hydrocatalytic desulphurisation of petroleum hydrocarbons.

It is well-known that organically combined sulphur cone tained in petroleum hydrocarbons may be removed by contacting the hydrocarbons with added hydrogen at elevated temperature and pressure in the presence of a sulcally combined sulphur is converted to hydrogen sulphide which may readily be removed from the treated hydrocarbons. Such processes are commonly called hydrofining processes and are usually carried out at temperatures and pressures which are optimum for the hydrogenation reaction. Thus, pressures of the order of 1000 lb./ sq. in. are employed and at such pressures there is a considerable consumption of hydrogen the cost of which is an important factor in the economics of the process.

A more recent development is the so-called autofining process wherein the petroleum hydrocarbons are contacted with a sulphur-resistant dehydrogenation-hydrogenation catalyst at a temperature and pressure such that the hydrogen required for desulphurisation is obtained by controlled dehydrogenation of the feedstock. Such a process forms the subject of United States Patents Nos. 2,573,726 and 2,574,445-51. The autofining process was originally operated at a fixed pressure and any hydrogen generated in excess of that required to maintain this fixed pressure was vented from the system. It was found, however, that increased desulphurisation was obtained by recycling all the hydrogen produced during the reaction and allowing the pressure to build up to an equilibrium pressure, and this method of operation forms the subject of United States Patent No. 2,648,623. 7

When autofining under equilibrium pressure conditions the pressure rises to a maximum within a relatively short period of to 25 hours, and thereafter falls gradually as the dehydrogenating activity of the catalyst decreases.

d States Patent C Patented July 23, 1957 The extent of the desulphurisation follows a similar pattern. The length of the run, i. e. the hours on stream before regeneration, is therefore governed by the rate at which the desulphurisation falls. For example, with a gas oil feedstock of 1.3% by weight sulphur when op erating at 2.0 v./v./hr. a bulked sulphur of 0.1% by weight is obtained over 200 hours on stream although by the end of this period the residual sulphur content is in the region of 0.3 to 0.4% by weight.

10 According to the present invention, a process for the hydrocatalytic desulphurisation of a petroleum feedstock, comprises contacting the feedstock in the presence of extraneous hydrogen with a sulphur-resistant dehydrogenation-hydrogenation catalyst under autofining condi- 5 tions of temperature and space velocity and at a pressure which ,is approximately equal to the equilibrium pressure to be obtained on'autofining the feedstock under the same conditions of catalyst, temperature and space velocity.

By operating in this manner, the fall-01f of the dehydrophur-resistant hydrogenation catalyst whereby the organigenating activity of the catalyst that occurs in autofining is retarded and the hours on stream before regenerationare considerably lengthened as compared with autofining. The process shows considerable economic advantage in that the overall hydrogen consumption is reduced to only afraction' of that required when carrying out a hydrofining operation at the conventional higher, pressures.

The temperature and space velocity required for any particular feedstock can easily be determined by experiment but in general the following ranges of conditions apply:

Temperature 750-800 F. Space velocity 1-5 v./v./hr.

The equilibrium pressure to be obtained on autofining 49 on alumina. Improved results, are obatined if the catalyst contains fluorine which is advantageously present in an amount between 1 and 4% by weight of the catalyst, since it has been found that the presence of the fluorine increases the, dehydrogenating activity of the catalyst and thereby enables higher equilibrium pressures to be built up resulting in increased desulphurisation. Methods of preparing cobalt oxide-molybdenum oxide catalysts containing fluorine are described in United States applica- 50 tion No. 311,429 filed September 25, 1952.

The invention will now be described with reference to the following examples:

EXAMPLE 1 Desulphurisation of Kuwait straight run gas oil containing 1.3% wt. sulphur to give a product of 0.1% wt. sulphur, using catalytic reformer gases containing ca. mol. hydrogen Hydrofinlng at autofining equilibrium Conventional hydrofining pressure Catalyst F activated Co-Mo Oo Mo oxides Co-Mo oxides Go-Mo oxides F activated oxides on alumina. on alumina. on alumina. on alumina. (Jo-Mo oxides on alumina.

Pressure, p. s. 1. ga... 500 500- 1,000 500.

Temperature, F... 780 800 780. 780 780.

Space Velocity, v./v 2..-. 2 4... 8 4.

Recycle Rate, S. C. F./B 6,400 4,000 4,000 4,000 4,000.

Hydrogen Consumption, S. O. F./B- 30 103 104 93.

EXAM LE 2 Desulphurisation of Kuwait straight run gas oil containing 1.3% wt. sulphur to give a prodl qt of 0.1% wt. sulphur. using pure hydrogen '99% rnol.)

' Hydrofinlng at autolining equilibrium Conventional hydroflmng pressure Catalyst-.. F activated Go-Mo Co-Mo oxides Co-Mo oxides Co'Mo oxides oxides on alumina. on alumina. on alumina. on alumina. Pressure, p. s. l. ,ga i g 1,000.. 500 1,000. Temperature, T... 7 I I V 780 7 780. Space Velocity, v./v./l1r 2 2 4 8. R OycleBate SKO. F ;/B-. 2,000-. 4,000 4,000-.. 4,000. Hydrogen Consumption, S. G. F./B p 208 127 210.

EXAMPLE 3 The following data show the eflectof hours on stream on residual sulphur content when desulphurising a Kuwait straight-run gas oil containing 1.3% wt. sulphur by: (a) autofining under equilibrium pressure conditions, -(b) hydrofining at the autofining equilibrium pressure using catalytic reformer hydrogen (ca. H2)

Autofining Hydrofining Catalyst F activated oe-Mo ox- F activated qo-Mo oxides on alumina. ides on alum na.

Temperature, F.. 780 780. SpaeeVelocltmvJm/hr 2 2. Recycle rate, S. O. F./B 2,000)(set at p. s. 1.. (M00. Initial pressure, p. s. l. ga 100i]. e20.

Hoursonstreamnn 10 1 50 100 10 50 .100 Pressure 1). s. 1. ga 285 265 220 125 360' 365 365 365 Residual sulphur, percent wt 0.04 0.09 0.19 0.15 0.04 0.04 0.05 0:07

We claim: denum supported on alumina and contains from 1 to 4% 1. A-processfor the hydrocatalytic'desulphurisation of by weight of fluorine. a petroleum feedstock, which comprises contacting the [4. A process according to claim 1, wherein said petrofeedstock in a reaction zone in the presence of extraneleurn feedstock is a gas oil. ous hydrogen with a' sulphur-resistant dehydrogenation- 40 I hydrogenation catalyst under autofining conditions of term References (31585111 the file of thls Pawnt perature and space velocity and establishing in the reac- UNITED STATES PATENTS s Zone from the y means 9 the a e u .1 3" 2 49 559 Layng etraal Feb 21, 1950 rogen apressure which 13 approximately equal to the 2 577 823 Stine D ec.11, 1951 init al autofining equilibrium pressure to be obtalnedpn .40 u ni the feedsto k u (16 th a e 'ti' n f Porter et a1 g- 1, catalyst t ernperature arid spai ce fleloc ity m co 1 OMS "o 2 6 3 0 f etal- ,3, 1953 2. A process according to claim 1, which is carried out 2697683 Engel et 1954 at a temperature within the range 750-800 F. and at a OTHER REFERENCES p c V y of h liquid feedstock of 1 Y-. 50 Hoog et al.: Oil & Gas Journal, vol. 52, No. 5, pages 3. A process accordingto claim 1, wherein said catalyst essentially consists of the oxides of cobalt and molyb-' 92 and 94 to 96 (June 8, 1953). 

1. A PROCESS FOR THE HYDROCATALYTIC DESULPHURISATION OF A PETROLEUM FEEDSTOCK, WHICH COMPRISES CONTACTING THE FEEDSTOCK IN REACTION ZONE IN THE PRESENCE OF EXTRANEOUS HYDROGEN WITH A SULPHUR-RESISTANT DEHYDROGENATIONHYDROGENATION CATAYLST UNDER AUTOFINING CONDITIONS OF TEMPERATURE AND SPACE VELOCITY AND ESTABLISHING IN THE REACTION ZONE FROM THE START BY MEANS OF EXTRANEOUS HYDROGEN A PRESSURE WHICH IS APPROXIMATELY EQUAL TO THE INITAL AUTOFINING EQUILIBRIUM PRESSURE TO BE OBTAINED ON AUTOFINING THE FEEDSTOCK UNDER THE SAME CONDITIONS OF CATALYST, TEMPERATURE AND SPACE VELOCITY. 